What is the meaning of Sleep Mode in Windows computer

Sleep mode is power saving options in the computer. 

Figure: Sleep Mode in Windows 7

Sleep mode is reduce the light consumption.

When you applied sleep mode, then it store all unsaved and open data in the RAM. And if the computer lost all power then all unsaved  and open data will be lost.

So here you can say that sleep mode is like a volatile memory.

What is the ideal time to applied sleep mode in computer?